Method of manufacturing slip sheets



1935 1... E. GROVE 2,02%17? METHOD OF MANUFACTURING SLIP SHEETS FiledNov. s, 1935 rove KQQvZQQSHM Patented Nov. 5, 1935 UNITED STATES ME'rnonI or MANUFACTURING snn- SHEETS .0 E. Grove,Hinsdale,Ill. ApplicationNovember 3, 1933, Serial No.'696,580

2 Claims.

This invention relates particularly to the protection of freshly printedsurfaces issuing from a printing-press, or printing-device, and has forits purpose the prevention of smearing, or offsetting,

5 of ink when the freshly printed surface comes in contact with anothersurface.

While the invention is especially useful in protecting freshly printedartificial cellulose surfaces, or the like, where the ink forming theprinted character or design remains mainly on the surface of the sheet,the invention is useful in connection with the preservation of freshlyprinted surfaces, generally.

In accordance with the present invention, a thin slip-sheet is subjectedto a point-embossing operation and in this manner provided on one of itssurfaces with a vast number of minute points which are closelyassociated, but preferably without regularity of position. Thepoint-embossing operation preferably is accomplished by means of aroller having its surface covered with sand-paper of medium coarseness.No. 1% sand-paper is well adapted to the purpose. The embossing roller,covered with sand-paper, coacts with another roller having a yieldingsurface so that a slip-sheet passed between the rollers will beembossed, without puncturing the slip-sheet.

After the slip-sheet has been produced, it may be used in the ordinarymanner as a slip-sheet between successive layers of freshly-printedpaper, freshly-printed sheets of cellophane or the like; or theslip-sheet may be wound with the' freshly-printed sheet'upon a suitabletake-up roll. In the use of the slip-sheet, the pointembossments areadjacent, the freshly-printed surface and serve to maintain an air filmbetween the freshly-printed surface and the-slip-sheet.

The invention is illustrate in a preferred embodiment in the. accompaying drawing, in which-- Fig. 1 is a broken plan view of a slip-sheetmade in accordance with the invention; Fig. 2, an edge elevational viewof the same; Fig. 3, a view illustrating the manner in which theslipsheet is formed; and Fig. 4, a view illustrating one method ofapplying the slip-sheet to a freshly printed surface.

In the illustration given, A designates the improved slip-sheet; B and Ba pair of embossing rolls; 0 and C, a printing-roll and coactingplaten-roll;

D, a take-up roll; and E, a guide-roll for directing the slip-sheet intocontact with the freshly-printed surface of the sheet being printed,which sheet is designated F.

The slip-sheet may comprise 'a very thin flexible sheetof any suitablematerial. Itmay be of paper, such as kraft paper, or it may be a verythin sheet of celluloid, or it may be a sheet of fabric produced fromviscose, or the like. Preferably, the slip-sheet is rather dense andtough, especially where it is to be used repeatedly. Ordinary thindrafting paper, or tracing paper, may be used. A very loose-fibred, softpaper is not so well adapted to the purpose.

Referring to Fig. 3, the embossing-roll B is shown as having its surfacecovered with a sheet I of sand-paper or the like which has its outersurface covered with minute sand-projections I. Ordinary sand-paper ofmedium grade (medium 15 fineness) serves the purpose very well. This maybe adhesively joined to the roll B, or otherwise applied.

The coacting impression-roll B preferably is provided with a surface ofsoft material, desig- 20 nated 2. A felt pad serves the purpose verywell. The embossing roller B may be positively rotated by any suitabledriving means, and .the coacting impression-roller B' may be an idler.Preferably, the roller B is provided with a heating ele- 25 ment,designated 3. This element may be a steam pipe, a gas burner, or anelectric heating element, as desired. It has been found desirable toapply heat during the embossing operation. Where the slip-sheet is ofcelluloid, the material is softened, 80 I and the embossed points,designated 4, are rather sharply defined and given a permanent set.Inasmuch as most papers contain some sizing, or, something in the natureof a hinder, the same effect, in varying degree, is obtained withvarious papers. By using minute embossing points on the embossing-roll,puncturing of the paper is avoided. This is especially desirable wherethe paper fibre is of a character to absorb ink when the paper ispunctured. That is, it is desirable 40 to avoid, as far as possible,getting ink upon or absorbed by the slip-sheet, especially where theslip-sheet is to be used repeatedly.

One very useful application of the invention is. to the purpose ofpreventing smearing or oifsetting of ink in the printing of cellulosetubes, such as are used as artificial sausage casings, or the. like.Cellulose tubes of this character are highly non-absorptive, so that inthe printing opera.- tion the ink characters stand upon the surface ofthe cellulose tube and do not dry quickly. It has been found that dangerof smearing is obviated by the use of the improved'slip-sheet.

It is preferred to use a very thin sheet of celluloid, because of itscleanly character and enduring quality. Where paper 'is used, it may bethinly coated with wax after the embossing operation, if desired. Thismay be done, for. example, by heating the wax and spraying it upon theembossed paper on the side which is provided with the embossed points.

For ordinary printing, where the, slip-sheets are to be used only once,or perhaps a few times, thin krait paper serves the purpose very well.

Preferably, the embossing-roll B is of small diameter, say about 2" indiameter, which gives something approaching a line contact and tends toproduce sharpness in the embossed points formed in the slip-sheet. Theembossed points need not be raised above the general surface of theslip-sheet more than a very minute traction of an inch, say .0002" to.0006". In ordinary sand-paper, the sand-points are closely butirregularly spaced, and thus the sand-paper serves as a die which willproduce irregularly located embossed points in the slip-sheet. This isof some advantage in avoidingcontacts with the ink. The exact height 0!the embossed points on the surface of the slip-sheet is not important,

construed as broadly as permissible, in view oi! the 10 prior art.

What I regard as new and desire to secure by Letters Patent is:

1. A method of producing a slip-sheet for the purpose set forth whichcomprises passing a thin 7 flexible sheet'between an embossing rollcovered with sand-paper and a coacting impression-roll.

2. A method as specified in claim 1, supplemented by applying heat tothe zone where the cents arebeing i'o'rmed.

ml. GROVI.

